Terpolymers containing vinylidene chloride, a cyclomonoolefine and another olefinic material



United States Patent 3,248,374 TERPOLYMERS CGNTAINING VINYLIDENE CHLORIDE, A CYCLOMONOOLEFINE AND ANUTHER OLEFENIC MATERIAL Edward Royals Covington, Richmond, Va., assignor to E. l. du Pont de Nemours and Company, Wilmington, Del, a corporation of Delaware No Drawing. Filed June 14, 1961, Ser. No. 116,966 8 Claims. (Cl. 26tl78.5)

This invention relates to the preparation of vinylidene chloride copolymers. More particularly, it relates to the preparation of vinylidene chloride copolymers having improved solubility in volatile organic solvents.

Coating flexible, transparent, water-sensitive films such as regenerated cellulose film, ethyl cellulose film, polyvinyl alcohol film, and the like with suitable coating compositions to render the base film moisture-resistant, heat-scalable, etc., is well known. Because of their toughness, flexibility, strength, transparency, heat-sealability and moisture-resistance, coatings composed of copolymers of vinylidene chloride with one or more polymerizable olefinic monomers have proven to be particularly useful. However, to achieve satisfactory moistureproofness, copolymers having rather high vinylidene chloride concentrations, i.e. in excess of 80% by weight, are necessary. Unfortunately, when prepared by the commonly used procedures of emulsion polymerization, copolymers containing 80% or more of vinylidene chloride are not sufilciently soluble in the common volatile organic solvents to be applied from solution using standard equipment. Hence, it has not been feasible to take full advantage of the superior properties of these copolymers as coatings for the various water-sensitive films.

It is an object of this invention to provide a process for preparing, with substantially complete conversion, copolymers containing 80% or more of vinylidene chloride which have improved solubility in volatile organic solvents and have excellent moistureproofness and coating characteristics. The preference is for a copolymer which is soluble to the extent of 10 parts per 40 parts of an 80/20 mixture of tetrahydrofuran and toluene at 65 C. Other objects will appear hereinafter.

The objects are accomplished in the process of preparing a vinylidene chloride copolymer by polymerizing 80-97%, by weight, preferably 80-93%, of vinylidene chloride with, correspondingly, 320%, by weight preferably 7-20%, of other monoolefinic material copolymerizable with vinylidene chloride, by adding prior to polymerization a small amount (from 01-20%), preferably 0.1- based on the Weight of the monomers, of a cyclomonoolefine, preferably cyclohexene, cycloheptene, cyclooctene and mixtures thereof.

It is essential that the polymerization modifier be added to the reaction charge either along with the mixture of polymerizable monomers prior to the initiation of the polymerization by the addition of the catalyst, or shortly thereafter but before any polymerization has occurred.

In a typical example of carrying out the process of this invention, 100 parts of a mixture of monomers containing 8097 parts, by weight, of vinylidene chloride, l9.9-2.9 parts, by weight, of an alkyl ester of acrylic or methacrylic acid having l-18 carbon atoms in the alkyl group, and 01-5 parts of either acrylic, methacrylic or itaconic acid is polymerized at the reflux temperature of the monomer mixture. The mixture is first dispersed by constant agitation in about 100 parts of an aqueous medium which contains a polymerization catalyst, an emulsifying agent and 1 to 3% of Cyclohexene based upon the total weight of the monomers. To insure sub- 3,248,374 Patented Apr. 26, 19%6 "ice as sodium lauryl sulfate or a sodium salt of an alkyl aryl sulfonate such as sodium dodecyl benzene sulfonate. It should be pointed out that neither the concentration nor composition of either the polymerization catalyst or emulsifying agent is a critical variable in the process of this invention. However, these materials should be of such nature and present in suflicient concentration to insure completion of the polymerization reaction within a reasonable period of time (l-Z hours) and without appreciable precipitation of the resulting copolymer.

Because of their low cost and availability, sodium salts of alkyl aryl sulfonates and sodium salts of sulfonated fatty alcohols are preferred as emulsifying agents for use in the process of this invention as well as for stabilizing the dispersions prepared in this manner. If desired, however, an ammonium or amine salt, or some other water-soluble metallic salt of these compounds may be used. Other suitable emulsifying agents are: salts of lOng chain fatty acids, salts of sulfonated paraflin oils, quaternary ammonium compounds containing long carbon chains and salts of mono-amides of dibasic acids.

As the polymerization catalyst, one or more compounds from the following classes may be used: hydrogen peroxide, organic peroxides, azines, ketazines, persulfates and perborates. Salts of iron, manganese or cobalt may also be used to increase the activity of these catalysts.

Cyclohexene is the preferred polymerization modifier for use in this invention. .Besides cyclo'hexene, cycloheptene and cyclooctene are also useful. Basically, these are all compounds having an unconjugated ring of at least 6 carbon atoms. In addition, they may have innocuous radicals attached to the carbons in the ring.

It should also be pointed out that the usefulness of the polymerization modifiers of this invention is not confined to the preparation of vinylidene chloride copolymers containing an alkyl ester of acrylic or methacrylic acid and either acrylic, methacrylic or itaconic acid. These modifiers may be also used in the preparation of copolymers formed by reacting -97% vinylidene chloride with 20-3% of one or more of the following monomers: phenyl methacrylate, cyclohexyl methacrylate, pcyclohexylphenyl methacrylate, methoxyethyl methacrylate, glycidyl methacrylate, chloroethyl methacrylate, 2- nitro-2-methyl-propyl-methacrylate, and the corresponding esters of acrylic acid, methyl alpha-chloroacrylate, octyl alpha-chloroacrylate, methyl isopropenyl ketone, acryl'onitrile, methacrylonitrile, methyl vinyl ketone, vinyl chloride, vinyl acetate, vinyl propionate, vinyl chloro- -acetate, vinyl bromide, styrene, vinyl naphthalene, ethyl vinyl ether, N-vinyl phthalimide, N-vinyl succinimide, N-vinyl carbazole, methylene diethyl malonate, acrylamide, methacrylamide or monoalkyl substitution products thereof, phenyl vinyl ketone, diethyl fumarate, diethyl maleate, methylene diethyl malonate, dichlorovinylidene fluoride, dimethyl itaconate, diethyl itaconate, dibutyl itaconate, vinyl pyridine, maleic anhydride, allyl glycidyl ether and other unsaturated aliphatic ethers described in US. Patent 2,160,943. These. compounds may be described as vinyl or vinylidene compounds having a single CH =C group. The most useful ones fall within the general formula:

EXAMPLE 1 The coating composition is prepared by adding a dispersing agent (sodium lauryl sulfate), a modifier" (cyclohexene), Vinylidene chloride, methyl acrylate, itaconic acid and water to a vessel fitted with a reflux condenser. After stirring this mixture to disperse the ingredients, a solution of ammonium persulfate, meta-sodium bisulfite, ferrous ammonium sulfate in water is added to catalyze the reaction. The mixture is refluxed by constant agitation and maintaining the temperature between 32 C. and 34 C. The mixture is stirred until refluxing ceases, thereby indicating the completion of copolymerization. This occurs after about 60 minutes. The ingredients used in the preparation are summarized below:

Parts by weight Dispersing agent (sodium lauryl sulfate) 4 Vinylidene chloride 366 Methyl acrylate 34 Itaconic acid 4 Catalyzing agent:

Ammonium persulfate 2.4 Meta-sodium bisulfite 2.4 Ferrous ammonium sulfate .012

Polymerization modifier (cyclohexene) 20 Water 400 Upon completing polymerization, the resulting copolymer is isolated by freezing and thawing the dispersion and filtering the precipitated copolymer. The copolymer is washed thoroughly with water and dried. The yield of copolymer is almost 100%. It is completely soluble; has a relative viscosity of 1.246; and the 20% solution of the copolymer in 80/20 tetrahydrofuran toluene is stable for 8 days.

As a control, the composition is prepared using all of the above ingredients except that the polymerization modifier (cyclohexene) is omitted. The resulting copolymer is not soluble and has a relative viscosity of 1.859.

The description of the tests that are performed on the copolymer follows:

Solubility is determined by placing 10 parts of dried copolymer in 40 parts of an 80/ 20 mixture of tetrahydrofuran and toluene at 65 C. and agitating the. mixture until all of the copolymer dissolves or until it is apparent that the copolymer is insoluble If the copolymer dissolves completely and remains in solution upon being cooled to room temperature, it is soluble. If, however, the copolymer fails to dissolve completely, or dissolves completely but precipitates or gels on being cooled to room temperature, the copolymer is considered insoluble.

Stability of a 20% solution of each copolymer in an /20 tetrahydrofuran-toluene mixture is indicated by the number of days until gelation of the solution or precipitation of the copolymer occurs. To be useful as a coating composition, a copolymer solution must be stable for at least one day.

Relative viscosity of the copolymer is determined by the usual procedure of measuring the viscosity at 25 C. for a 1% weight/volume solution of the copolymer in tetrahydrofur-an and dividing this value by the viscosity of the solvent at the same temperature.

The effectiveness of the copolymer is tested by coating it on a regenerated cellulose film. The coating is applied by passing the film through a coating bath containing a 20% solution of the copolymer in the 80/20 tetrahydrofuran/ toluene mixture. Excess solution is doctored from the film surface. The coated film is then dried and tested. It has a coating weight, as dried, of- 5.75 grams/ square meter; an initial permeability value (IPV) of 72 grams of water lost/ square meters/hour; and heatseal strengths at C. and C. of 567 and 657 grams/1.5 inches, respectively.

The description of the tests that are performed on the coated film follows:

Coating weight is determined for cellulosic film by soaking the coated film in a hot solution of a sodium alkyl aryl sulfonate in acetic acid and stripping the coating from the film. The stripped coating in the form of a thin film is dried and weighed.

IPV-Initial permeability value is a measure of the moistureproofness of the coated film. The definition for and test for moistureproofness (IPV) are set forth in U.S. Patent 2,147,180 to Ubben. In general, a coated film having an IPV of 100 grams of water lost/ 100 square meters/hour or less is considered to have satisfactory moistureproofness.

Heat-seal strength is measured by cutting a piece of the coated film 4 x 10" with the grain running in the long or machine direction into two pieces 4" x 5" each. The two pieces are superimposed so that opposite surfaces are in contact. The two pieces of superimposed film are then sealed together at each end at right angles to the grain by applying a wide sealing bar under carefully controlled conditions of temperature (120 C. and 130 C.), pressure (5 p.s.i.) and contact time second). The sealed sheets are then cut in half at right angles to the grain. From the center of the two resulting pieces, 1 /2 wide strips parallel to the grain are cut. The resulting four sets of strips are tested by opening each set of strips at the free ends, placing them in a Suter testing machine and pulling them apart. The highest force in grams required to pull the strips apart is taken as a measure of the heatseal bond strength.

EXAMPLE 2 The following ingredients are charged into a threenecked round bottom flask equipped with a stirrer and condenser, and then heated at 32-34 C. while being agitated until the polymerization reaction is complete:

Parts Water 400 Sodium lauryl sulfate (solids basis) 4.0 Vinylidene chloride 370 Methyl acrylate 30 Itaconic acid -2-.. 4

Cyc'loheptene 20 Ammonium persulfate 2.4 Sodium toluene sulfinate 2.4 Ferrous ammonium sulfate 0.012

The reaction time would be approximately 80 minutes, and the polymer would behave just as that illustrated in Example 1.

n I3 EXAMPLE 3 The same ingredients are used as in Example 2 except the catalyst system is changed to 1.20 grams of 30% hydrogen peroxide and 4.12 grams of ferrous ammonium 6 carried out at any temperature from room temperature (20 C.) to 100 C. or higher and under a pressure of 1 atmosphere to 100 atmospheres or higher.

The coatings may be applied in accordance with any sulfate. The reaction time would be 60 minutes and the k g i i .They y be applied by EXAMPLE 4 film, or applied manually by brushing or the like. The The following ingredients are charged into a pop bottle thickness of thaicoatingsntay be adjltsted in accordance which is then sealed and tumbled in a constant temperature 10 Wlth methods Well known the coating F a at 550 C. for five hours: The preferred base material for use in this inventlon 1s 21 Parts regenerated cellulose shaped art1cle, e.g. regenerated cellu- Water 100 lose Other base materials which may be used in the Sodium lauryl sulfate (Solids basis) 2 invention include wood, paper, films and other shaped arvinylidene chloride 925 ticles of cellulose acetate, cellulose propionate, cellulose M ethyl acrylate 7.5 acetatebutyrate, ethyl cellulose, hydroxyethyl cellulose, Itaconic acid 1'0 hydroxypropyl cellulose, carboxymethyl cellulose, the Cy c1 0 octene 4.0 pilllfyi esterslsuch das polyefhylene terephthalate, the polyo e ns, po yamr es, me a s, e c. 'Azo'dusobutyromtnle The materials of this invention are used advantageously AZO eata'lysts are not active at the lower temperature, as packaging materials for foods, cigarettes and the like. the Polymefilation must be Carried Out in a Pressure They provide flexible, strong materials that, due to imvessel at slightly higher temperatures. The poly r s proved heat-seal strength, can be easily converted to packcomparable in properties to that described in Example 1. ages, Thi coating does not detract from the transparency of the base material. EXAMPiLES 5 6 As many widely different embodiments can be made foltowlhg examples Illustrate the p p h without departing from the scope of the invention, it is yh e f eopolymels y the Process of t understood that the invention is not limited except as ventron using various concentrat1ons of the polymerization d fi d i h d d l i modifier? these examples, the copolymefs a Having fully disclosed the invention, what is claimed is: Paired y eomblhlng vinylidene chloride, y acrylate 1. In the process of preparing a vinylidene chloride and itaconic acid in the ratio Of 92.5/75/1. co olymer by polymerizi g in an aqueous emulsion sys- The 'gehef a1 Proeedllfe used in Preparing these P Y- tern, until substantially complete conversion of all polymmer samples is similar to that described in Example 1 and i bl mgnome s present h taken place to id consists of combining the following ingredients in a round polymer, 8Q 97%, b i h f i lid hlo id with, bottom flask q pp With a condenser, thermometer and correspondingly, 320%, by weight, of other monoolefinic stirrer, heating the IniXtufe at 3244: While agitating material copolymerizable with vinylidene chloride having until the polymerization reaction is complete: the formula Sodium lauryl sulfate 4 parts (solids basis). R Vinylidene chloride 370 parts. 40 J; Methyl acrylate 30 parts. I Itaconic acid 4 parts. X Polymerization modifier As shown in Table I. Where R is Selected from the hP eensistlhg 0f y f- Ammonium lf t (ASP) As shown i m L gen, a halogen and a saturated allphatrc radical and X 18 Meta-sodium bisulfite (MSB) As shown in Table 1. selected from the group consistmg of Ferrous ammonium sulfate 0.012 part. 1 C H COOH Water 400 parts. 0 O O The amount of modifier, ammonium persulfate and Lt Lt l meta-sodium bisulfite; the reaction time; and the properl ties of the copolymer are shown in Table 1. H

Table I Parts Parts Parts Reaction Soluble in Stability of Relative Example Modifier Modifier ,ASP MSB Time, THF/ S lut s s tv Minutes Toluene Days Control None 1.2 0,6 50 No 1.859 5 Oyclohexene 4 1.6 0.8 88 Yes 2 1.537 6. 2-... Cycl0hexe11e 2.4 2.4 80 Yes .2 2 1.448

From the foregoing examples it is evident that a wide -OC H CONH CONHR', and CONR in variety of ingredients may enter the preparation of the which is y the improvement Comprising the p films. To obtain increased anchorage at high relative of eddihg Prior to Polymerization based on the humidities, films sensitive to water vapor may be pre- Welght of the monomers of Compound Seletited from the treated with anchoring resins, such as those disclosed in group conslstmg of cyclohexene cyclohepmne and cycle" US. Patents 2,159,007; 2,280,829; 2,432,542; 2,533,557 Octeneand 2,546,575. The films, particularly regenerated cellu- A.process as m clalm 1 wherem sald cyclomono' lose film, may contain softeners or other constituents such a i cyclohexexie' l 1 h 1 as pigments, dyes, delusterants, plasticizers, etc., if desired. 0 olefine sgg iz i jg g c alm w erem Sal cyc Omono The important concept here and the one basic to this in- 4. A process as in claim 1 wherein said cyclomonovention resldes 1n the use of a polymer1zat1on modifier olefine is cyclooctene 1n the preparation of the copolymer of '8 0-97% by weigh 5. A process as in claim 1 wherein said other mono- Ot vlhyhdehe ehlerlde and 340% y Welght Of a p y olefinic material is an alkyl acrylate having 1-18 carbon izable mono-olefinic monomer. Polymerization may be atoms in the alkyl group.

6. A process as in claim 1 wherein said other monoolefinic material is an alkyl methacrylate having 1-18 carbon atoms in the alkyl group.

7. A process as in claim 1 wherein said other monoolefinic material is methyl acrylate.

8. A process as in claim 1 wherein said other monoolefinic material is methyl acrylate and itaconic acid.

References Cited by the Examiner UNITED STATES PATENTS 2,377,095 5/1945 Muskat 26078.4

3 2,616,884 11/1952 Marous 26092.8 3,041,208 6/1962 Hay et a1 26029.6 3,058,962 10/1962 Trofimow et al. 26087.7

5 FOREIGN PATENTS 576,830 4/1946 Great Britain.

591,944 9/ 1947 Great Britain.

674,728 7/1952 Great Britain.

10 JOSEPH L. SCHOFER, Primary Examiner.

LEON J. BERCOVITZ, Examiner. 

1. IN THE PROCESS OF PREPARING A VINYLIDENE CHLORIDE COPOLYMER BY POLYMERIZING IN AN AQUEOUS EMULSION SYSTEM, UNTIL SUBSTANTIALLY COMPLETE CONVERSION OF ALL POLYMERIZABLE MONOMERS PRESENT HAS TAKEN PLACE TO SAID COPOLYMER, 80-97%, BY WEIGHT, OF VINYLIDENE CHLORIDE WITH, CORRESPONDINGLY, 3-20%, BY WEIGHT, OF OTHER MONOOLEFINIC MATERIAL COPOLYMERIZABLE WITH VINYLIDENE CHLORIDE HAVING THE FORMULA 